Membrane properties and response to light of single neurons of the retina will be measured after application of perfusates of various ionic composition and after injection of agents capable of altering intracellular concentrations of various ions. Techniques will be devised to detect defective vision in the mouse and these techniques will be applied to existing mutant stocks in a search for mutants bearing visual defects of a discrete nature. BIBLIOGRAPHIC REFERENCES: Pinto, L.H., Brown, J.E., and Brown, P.R. (1976) Arsenazo III. A metallochromic dye for detection of changes of intracellular ionized calcium in Limulus ventral photoreceptors. Biophysical J. abstract. Pinto, L.H. and Ostroy, S.E. (1976) Ionizable groups affecting the permeability of the vertebrate photoreceptor membrane II. Studies using intracellular recordings. Manuscript submitted to J. Gen. Physiol.